Poly(ethylene carbonate) (PEC) is a flexible, biocompatible, and biodegradable material with high gas barrier properties, particularly for O2. It is made via the ring opening polymerization of ethylene carbonate (EC) or by the copolymerization of ethylene oxide (EO) and CO2. Ring opening polymerization of EC initiated by KOH or Sn(OAc)2 at high temperature leads to poly(ethylene oxide-co-ether carbonate) rather than PEC. The high reaction temperatures required for this route cause the elimination of CO2 during polymerization. The alternating copolymerization of epoxides and CO2 to form polycarbonates was originally discovered by Inoue in 1969. Since then, numerous catalyst systems have been developed for epoxide/CO2 copolymerization (see, for example, Coates and Moore, Angew. Chem. Int. Ed. 2004, 43, 6618-6639; Super and Beckman, Trends Polym. Sci. 1997, 5, 236-240; Darensbourg, and Holtcamp, Coord. Chem. Rev. 1996, 153, 155-174). Various systems for EO/CO2 copolymerization based on Zn, Al, or double metal cyanide species have been reported; however, they require high CO2 pressure and suffer from low catalytic activities.